JP2011225664A - Rubber-steel cord composite - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber-steel cord composite that has excellent workability and markedly excellent tensile characteristics, adhesiveness after short-time vulcanization and heat-resistant adhesiveness.SOLUTION: The rubber-steel cord composite includes a rubber composition that comprises a rubber component, sulfur and a sulfenamide-based vulcanization accelerator having a specific structure, to which steel cords that have a brass-plated layer on the peripheral surface in which the content of phosphorus contained as oxide in a wire surface layer region from the surface of the brass plating layer to depth of 5 nm inward in a wire radial direction is ≤1.5 atom% are adjacent.

Description

  The present invention relates to a rubber-steel cord composite, a rubber composition containing a specific sulfenamide-based vulcanization accelerator, and a single wire of steel wire with a low content of phosphorus contained as an oxide in the surface layer region of brass plating Alternatively, the present invention relates to a rubber-steel cord composite in which workability and adhesion between a rubber-steel cord and the like are improved by using a steel cord formed by twisting a plurality of steel wires.

  Conventionally, in rubber articles such as radial tire belts, carcass body plies, and various industrial belt members, steel wires coated with brass or a steel cord formed by twisting a plurality of them are covered with rubber. Reinforcing effects have been obtained by using the above. In this case, in order to sufficiently exert the reinforcing effect, it is necessary to ensure sufficient adhesion between the steel cord and the rubber. From this viewpoint, the ratio of copper and zinc in brass plating and plating Optimization of the thickness has been studied, and certain knowledge has been established so far.

  In general, the performance required for bonding between the brass-plated steel cord and the coating rubber is not simply that the initial adhesion is good, but rubber products such as tires were exposed to a deteriorated environment during actual use. In this case, it is necessary to satisfy various conditions such as not causing a failure due to deterioration of the adhesive interface, preventing troubles in the manufacturing process of rubber products such as tires, and suppressing the blending cost.

Therefore, the present applicants are steel wires and steel cords excellent in adhesiveness with rubber, for example, a steel wire in which a brass plating layer is applied to the peripheral surface of the wire, from the surface of the brass plating layer. A steel wire for reinforcing rubber articles in which the content of phosphorus contained as an oxide in the wire surface layer region up to a depth of 5 nm inward in the wire radial direction is suppressed to 1.5 atomic% or less, and a plurality of these wires are twisted Proposed steel cords (for example, see Patent Document 1), and 0.1 to 5 parts by weight of maleimide resin and two tert-butyl groups for a rubber component containing 50% by weight or more of natural rubber A rubber composition containing 0.5 to 8 parts by weight of a bisphenol compound having at least one higher fatty acid, and a brass plating layer on the peripheral surface A single wire of steel wire having a phosphorus content of not more than 1.5 atomic% in the surface region of the wire from the surface of the brass plating layer to a depth of 5 nm inward in the radial direction of the wire, or A rubber-steel cord composite (see, for example, Patent Document 2) composed of a steel cord formed by twisting a plurality of steel wires is proposed.
The rubber-steel cord composites described in these documents 1 and 2 can exhibit excellent adhesive properties that have never been seen before. However, for further workability and further adhesiveness of rubber-steel cords. At present, the appearance of excellent rubber-steel cord composites is anxious.

  On the other hand, rubber compositions such as coating rubber reinforced with steel cords are required to have high elasticity, low heat build-up, deterioration resistance, adhesiveness, etc. Especially, this rubber-steel cord composite is highly reinforced. In order to exert the effect and obtain the reliability, it is necessary to stably bond the rubber-steel cord composite with little change with time.

  In addition, when bonding rubber and metal such as steel wire, a method of simultaneously bonding rubber and metal, that is, a direct vulcanization bonding method is known. In this case, rubber vulcanization and rubber and metal bonding are performed. For simultaneous bonding, it is considered useful to use a sulfenamide vulcanization accelerator that gives a slow effect to the vulcanization reaction.

また、このＤＣＢＳの加硫反応の遅効性よりも更に遅効性が必要な場合は、スルフェンアミド系加硫促進剤とは別に、加硫遅延剤を併用することが行われている。なお、市販されている代表的な加硫遅延剤としては、Ｎ−（シクロヘキシルチオ）フタルイミド（以下、「ＣＴＰ」と略す）が知られているが、このＣＴＰをゴムに多量に配合すると、加硫ゴムの物理的物性に悪影響を及ぼし、かつ、加硫ゴムの外観の悪化及び接着性に悪影響を及ぼすブルーミングの原因になることは既に知られている。 Among the commercially available sulfenamide vulcanization accelerators, for example, N, N-dicyclohexyl-2-benzo represented by the following formula can be used as a vulcanization accelerator that most delays the vulcanization reaction. Thiazolylsulfenamide (hereinafter abbreviated as “DCBS”) is known.

In addition, in the case where the delayed effect is required more than the delayed effect of the vulcanization reaction of DCBS, a vulcanization retarder is used in combination with the sulfenamide vulcanization accelerator. Note that N- (cyclohexylthio) phthalimide (hereinafter abbreviated as “CTP”) is known as a typical vulcanization retarder commercially available. It has already been known that it causes blooming which adversely affects the physical properties of vulcanized rubber, and which deteriorates the appearance and adhesion of vulcanized rubber.

Furthermore, examples of the sulfenamide-based vulcanization accelerator other than the above-described DCBS include, for example, bissulfenamide represented by a specific formula (see, for example, Patent Document 3) and benzothia using amines derived from natural fats and oils as raw materials. A solyl sulfenamide vulcanization accelerator (see, for example, Patent Document 4) is known.
However, these sulfenamide-based vulcanization accelerators described in Patent Documents 3 and 4 are only descriptions of rubber physical properties, and there is no description or suggestion about adhesive performance. There is no description or suggestion that a sulfenamide compound can be newly used as a vulcanization accelerator for rubber.

Furthermore, some methods for producing sulfenamide compounds used in the present invention are known, for example, in Patent Documents 5, 6 and 7. These compounds are used as vulcanization accelerators for rubber. There is no description or suggestion about the ability to be newly used and the adhesion performance with the steel cord provided by this accelerator.
Further, as an approximation to the present invention, for example, a vulcanization accelerator exemplified by N-methyl-cyclohexyl-2-benzothiazolylsulfenamide (see Patent Document 8), N-tert-butyl-cyclohexyl- Although vulcanization accelerators (see Patent Document 9) exemplified by 2-benzothiazolylsulfenamide and the like are known, their structural skeletons are different from those of the present invention and can be distinguished. The effects and the like are inferior to those of the present invention.

International Publication No. WO2002 / 066672 (Claims, Examples, etc.) JP-A-2004-82878 (Claims, Examples, etc.) JP-A-2005-139239 (Claims, Examples, etc.) Japanese Patent Laying-Open No. 2005-139082 (Claims, Examples, etc.) JP-A-2005-139239 (Claims, Examples, etc.) EP0314663A1 Publication (Claims, Examples, etc.) British Patent No. 1177790 (Claims, Examples, etc.) French Patent No. 2037001 (Claims, Examples, etc.) Japanese Patent Publication No.49-11214 (Claims, Examples, etc.)

  In view of the above-described conventional problems, the present invention intends to solve this problem, without using a vulcanization retarder that may cause problems such as deterioration of physical properties of rubber after vulcanization and blooming. A rubber composition containing a vulcanization accelerator having a vulcanization retarding effect equivalent to or better than that of DCBS, a single wire of steel wire with a low content of phosphorus contained as an oxide in the surface layer region of brass plating, or a plurality of steel wires Adhesion with steel wires and steel cords that use steel cords made by twisting books together, with extremely low rubber burns, excellent workability, and little change over time in compounded rubber and stable adhesion An object of the present invention is to provide a rubber-steel cord composite that is remarkably excellent in properties.

  As a result of intensive studies on the above conventional issues and the like, the present inventor has found that a rubber composition containing a specific sulfenamide vulcanization accelerator and the inclusion of phosphorus contained as an oxide in the surface layer region of brass plating In order to complete the present invention, it is found that a rubber-steel cord composite for the above purpose can be obtained by using a single wire of a small amount of steel wire or a steel cord formed by twisting a plurality of steel wires. It has come.

（２） ゴム成分１００質量部に対して、硫黄０．３〜１０質量部、上記一般式（Ｉ）で表されるスルフェンアミド系加硫促進剤０．１〜１０質量部、前記ブラスめっき層全体における銅および亜鉛の総量に対する銅の比率が６０〜７０質量％であり、かつ、前記ワイヤ表層領域における銅および亜鉛の総量に対する銅の比率が１５〜４５原子％である上記（１）記載のゴム−スチールコード複合体。
（３） 前記ブラスめっき層の平均厚みが０．１３〜０．３０μｍである上記（１）又は（２）記載のゴム−スチールコード複合体。
（４） 前記スチールコードは、スチールワイヤの単線、または該スチールワイヤの複数本を撚り合わせてなる上記（１）〜（３）の何れか一つに記載のゴム−スチールコード複合体。
（５） 前記スチールワイヤの直径が０．４０ｍｍ以下である上記（４）記載のゴム−スチールコード複合体。
（６） ゴム組成物に、更に有機酸のコバルト塩をコバルト量として、ゴム成分１００質量部に対し、０．０３〜３質量部含む上記（１）〜（５）の何れか一つに記載のゴム−スチールコード複合体。
（７） 上記一般式（Ｉ）中のＲ^１２〜Ｒ^１５が水素原子である上記（１）〜（６）の何れか一つに記載のゴム−スチールコード複合体。
（８） 上記一般式（Ｉ）中のＲ^１１が水素原子であり、ｘが１である上記（１）〜（７）の何れか一つに記載のゴム−スチールコード複合体。
（９） ゴム成分が、天然ゴム及びポリイソプレンゴムの少なくとも一方を含む上記（１）〜（８）の何れか一つに記載のゴム−スチールコード複合体。
（１０） ゴム成分が、５０質量％以上の天然ゴム及び残部を合成ゴムよりなる上記（１）〜（８）の何れか一つに記載のゴム−スチールコード複合体。 That is, the present invention resides in the following (1) to (10).
(1) A rubber composition containing a rubber component, sulfur, and a sulfenamide-based vulcanization accelerator represented by the following general formula (I) has a brass plating layer on the peripheral surface, and the brass plating A steel cord in which the content of phosphorus contained as an oxide in the surface region of the wire up to a depth of 5 nm from the surface of the layer to the inside in the wire radial direction is adjacent to 1.5 atomic% or less is adjacent to the rubber -Steel cord composite.

(2) 0.1 to 10 parts by mass of sulfur, 0.1 to 10 parts by mass of the sulfenamide-based vulcanization accelerator represented by the general formula (I), 100 parts by mass of the rubber component, and the brass plating The above (1) description, wherein the ratio of copper to the total amount of copper and zinc in the entire layer is 60 to 70% by mass, and the ratio of copper to the total amount of copper and zinc in the wire surface layer region is 15 to 45 atomic% Rubber-steel cord composite.
(3) The rubber-steel cord composite according to (1) or (2), wherein the brass plating layer has an average thickness of 0.13 to 0.30 μm.
(4) The rubber-steel cord composite according to any one of (1) to (3), wherein the steel cord is a single wire of steel wire or a plurality of the steel wires twisted together.
(5) The rubber-steel cord composite according to (4), wherein the steel wire has a diameter of 0.40 mm or less.
(6) The rubber composition further includes 0.03 to 3 parts by mass of 100 parts by mass of a rubber component, with the cobalt salt of an organic acid as a cobalt amount, as described in any one of (1) to (5) above. Rubber-steel cord composite.
(7) The rubber-steel cord composite according to any one of (1) to (6), wherein R ^{12 to} R ¹⁵ in the general formula (I) are hydrogen atoms.
(8) The rubber-steel cord composite according to any one of (1) to (7), wherein R ¹¹ in the general formula (I) is a hydrogen atom and x is 1.
(9) The rubber-steel cord composite according to any one of (1) to (8), wherein the rubber component contains at least one of natural rubber and polyisoprene rubber.
(10) The rubber-steel cord composite according to any one of the above (1) to (8), wherein the rubber component is a natural rubber of 50% by mass or more and the balance is a synthetic rubber.

  According to the present invention, there is provided a rubber-steel cord composite that is excellent in workability and has excellent tensile properties, short-time vulcanization adhesion, and heat-resistant adhesion.

Hereinafter, embodiments of the present invention will be described in detail.
The rubber-steel cord composite of the present invention comprises a rubber composition containing a rubber component, sulfur, and a sulfenamide-based vulcanization accelerator represented by the following general formula (I). And a steel cord having a content of phosphorus of 1.5 atomic% or less adjacent to the surface of the brass plating layer as an oxide in a wire surface layer region having a depth of 5 nm inward in the wire radial direction. It is characterized by that.

The rubber component used in the present invention is not particularly limited as long as it is a rubber used in a rubber-steel cord composite, and can be sulfur-crosslinked if it is a rubber component having a double bond in the main chain. The sulfenamide vulcanization accelerator represented by (I) functions, and for example, natural rubber and / or diene synthetic rubber is used. Specifically, at least one of natural rubber, polyisoprene rubber, styrene-butadiene copolymer, polybutadiene rubber, isoprene rubber, ethylene-propylene-diene copolymer, chloroprene rubber, halogenated butyl rubber, acrylonitrile-butadiene rubber and the like. Can be used.
Preferably, it preferably contains at least one of natural rubber and polyisoprene rubber from the viewpoint of adhesion to steel wires and steel cords. Further, from the viewpoint of further durability of the rubber-steel cord composite, the rubber component However, it is desirable that 50% by mass or more of the natural rubber and the balance are made of at least one synthetic rubber.

  The sulfenamide-based vulcanization accelerator represented by the general formula (I) of the present invention has not been reported so far in combination with a cobalt-based adhesive, and N, N-dicyclohexyl-2-benzothia Rubber-steel used for thick rubber products and pneumatic tires, which has the effect of retarding vulcanization equivalent to zolylsulfenamide, and has excellent adhesion durability in direct vulcanization adhesion to steel wires and steel cords. It can be suitably used for the rubber composition of the cord composite.

In the present invention, in the sulfenamide compound represented by the general formula (I),
(1) When R ¹¹ is a hydrogen atom, R ^{1 to} R ¹⁰ are a hydrogen atom (except when all are hydrogen atoms), a linear alkyl group having 1 to 4 carbon atoms, or a carbon atom having 3 to 4 carbon atoms. Branched alkyl groups, which may be the same or different,
(2) When R ¹¹ is a linear alkyl group having 1 to 10 carbon atoms or a branched alkyl group having 3 to 10 carbon atoms, R ^{1 to} R ¹⁰ are hydrogen atoms (provided that all are hydrogen atoms) Except), a straight-chain alkyl group having 1 to 4 carbon atoms or a branched alkyl group having 3 to 4 carbon atoms, which may be the same or different,
(3) In the case of the above (1) and (2), R ^{12 to} R ¹⁵ are a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms or an alkoxy group, a branched alkyl group having 3 to 4 carbon atoms or an alkoxy group. Groups, which may be the same or different.
The sulfenamide compound represented by the above general formula (I) of the present invention, that is, the sulfenamide compound represented by the above (1) and (3), and the above (2) and (3) In particular, the sulfenamide compound has good vulcanization acceleration performance and can improve adhesion performance.

In the compound represented by the above general formula (I), R ^{1 to} R ¹⁰ in the above (1) or (2) exclude all cases where they are hydrogen atoms (cyclohexyl), so that at least one of the cyclohexyl rings is A straight-chain alkyl group having 1 to 4 carbon atoms or a branched alkyl group having 3 to 4 carbon atoms, which may be the same or different. Specific examples of the linear alkyl group having 1 to 4 carbon atoms or the branched alkyl group having 3 to 4 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec -Butyl group, tert-butyl group and the like.
In R ^{1 to} R ¹⁰ of the above (1) or (2), preferably, R ¹ , R ² , R ⁹ , and R ¹⁰ are hydrogen atoms, carbons, etc. from the viewpoint of obtaining a sufficiently long scorch time. A linear alkyl group having 1 to 4 carbon atoms or a branched alkyl group having 3 carbon atoms, and R ^{3 to} R ⁸ are preferably hydrogen atoms (provided that all of R ^{1 to} R ¹⁰ are hydrogen atoms) More preferably, at least one of R ¹ , R ² , R ⁹ , and R ¹⁰ is a branched alkyl group having 3 to 4 carbon atoms (when all are other than branched alkyl groups having 3 to 4 carbon atoms, the remainder is hydrogen) Particularly preferably ^one of R ¹ , R ² and one of R ⁹ , R ¹⁰ are both carbon atoms (at positions 2 and 6 of the cyclohexyl ring). A branched alkyl group of 3 to 4 (isopropyl group, isobuty Group, sec- butyl group, a tert- butyl group), the remaining two are hydrogen atom ^and R 3 to R ⁸ is a hydrogen atom is preferable.

R ^{11 in} the case (1) is a hydrogen atom, and R ¹¹ in the case (2) is a linear alkyl group having 1 to 10 carbon atoms or a branched alkyl group having 3 to 10 carbon atoms. It is. Specific examples of the linear alkyl group having 1 to 10 carbon atoms or the branched alkyl group having 3 to 10 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec -Butyl group, tert-butyl group, n-amyl group (n-pentyl group), isoamyl group (isopentyl group), neopentyl group, tert-amyl group (tert-pentyl group), n-hexyl group, isohexyl group, n -Heptyl group, isoheptyl group, n-octyl group, iso-octyl group, nonyl group, isononyl group, decyl group and the like.
In R ¹¹ of the above (2), preferably, from the viewpoint of effects such as ease of synthesis and raw material cost, a straight chain having 1 to 8 carbon atoms or a branched alkyl group having 3 to 8 carbon atoms, and further having 1 to 1 carbon atoms. 5 is a straight chain or branched alkyl group having 3 to 5 carbon atoms, more preferably a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a sec-butyl group, A tert-butyl group, particularly a methyl group and an ethyl group are preferred.

Furthermore, in the compound represented by the general formula (I), R ^{12 to} R ¹⁵ in the above (3) are a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms or an alkoxy group, and having 3 to 4 carbon atoms. A branched alkyl group or an alkoxy group, which may be the same or different, and among them, all are hydrogen atoms, or R ¹² and R ¹⁴ are linear alkyl groups having 1 to 4 carbon atoms or An alkoxy group, a branched alkyl group having 3 to 4 carbon atoms, or an alkoxy group is preferable. Furthermore, when R < ¹² > -R < ¹⁵ > is a C1-C4 alkyl group or an alkoxy group, it is preferable that it is C1-C1, especially preferably that all are hydrogen atoms. This is because in any case, the ease of synthesis of the compound and the vulcanization rate do not slow down.
Specific examples of R ^{12 to} R ¹⁵ of the sulfenamide compound represented by the general formula (I) include a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, Examples include isobutyl, sec-butyl, tert-butyl, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, and tert-butoxy.

Furthermore, x in the sulfenamide compound represented by the above general formula (I) represents an integer of 1 or 2, preferably 1.
In addition, R ^{1 to} R ¹⁰ in the sulfenamide compound represented by the general formula (I) are each a functional group other than a hydrogen atom, a straight chain having 1 to 4 carbon atoms, or a branched alkyl group having 3 to 4 carbon atoms. (For example, n-octadecyl group, etc.) or a straight chain or branched alkyl group having more than 5 carbon atoms, when all are hydrogen atoms, or when R ¹¹ is a hydrogen atom, straight chain having 1 to 10 carbon atoms Alternatively, when each functional group other than a branched alkyl group having 3 to 10 carbon atoms (for example, n-octadecyl group or the like) or a linear or branched alkyl group having more than 10 carbon atoms, the effect of the present invention is exhibited. In some cases, the Mooney scorch time is shortened, so that it is easy to burn and the workability is deteriorated, the adhesiveness is lowered, or the vulcanization performance and the rubber performance are lowered. Further, when x is 3 or more, it is not preferable in terms of stability.

In the present invention, typical examples of the compound represented by the general formula (I) include N, N-methylcyclohexyl-2-benzothiazo in the sulfenamide compounds represented by the above (1) and (3). -Rulsulfenamide, N, N-ethylcyclohexyl-2-benzothiazolsulfenamide, N, N-propylcyclohexyl-2-benzothiazolsulfenamide, N, N-butylcyclohexyl-2-benzothiazo- Rusulfenamide, N, N-isopropylcyclohexyl-2-benzothiazolsulfenamide, N, N-tert-butylcyclohexyl-2-benzothiazolsulfenamide, N, N-2,6-dimethylcyclohex Xyl-2-benzothiazolsulfenamide, N, N-2,6-diethylcyclohexyl 2-benzothiazol sulfenamide, N, N-2,6-dipropylcyclohexyl-2-benzothiazol sulfenamide, N, N-2,6-dibutylcyclohexyl-2-benzothiazol sulfenamide N, N-2,6-diisopropylcyclohexyl-2-benzothiazolsulfenamide, N, N-2,6-ditert-butylcyclohexyl-2-benzothiazolsulfenamide, and the like.
In the sulfenamide compounds represented by the above (2) and (3), N, N- (2,6-dimethylcyclohexyl) methyl-2-benzothiazolsulfenamide, N, N- (2,6 -Dimethylcyclohexyl) ethyl-2-benzothiazolsulfenamide, N, N- (2,6-diethylcyclohexyl) methyl-2-benzothiazolsulfenamide, N, N- (2,6-diethyl) Cyclohexyl) ethyl-2-benzothiazolsulfenamide, N, N- (2,6-diisopropylcyclohexyl) ethyl-2-benzothiazolsulfenamide, N, N- (2,6-ditert- And butylcyclohexyl) ethyl-2-benzothiazolsulfenamide. These compounds can be used alone or in admixture of two or more (hereinafter, simply referred to as “at least one”).
Preferably, from the viewpoint of further adhesion performance, N, N-methylcyclohexyl-2-benzothiazolsulfenamide, N, N- (2,6-dimethylcyclohexyl) ethyl-2-benzothiazolsulfenamide N, N- (2,6-diisopropylcyclohexyl) ethyl-2-benzothiazolsulfenamide is preferably used.
Also, general-purpose vulcanization accelerators such as N-tert-butyl-2-benzothiazolsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolsulfenamide (CBS), dibenzothiazolyl disulfide (MBTS), etc. It is also possible to use in combination.

The following method can be mentioned as a preferable manufacturing method of the sulfenamide compound represented by the general formula (I) of the present invention.
That is, N-chloroamine and bis (benzothiazol-2-yl) disulfide prepared in advance by the reaction of a corresponding amine and sodium hypochlorite are reacted in an appropriate solvent in the presence of an amine and a base. If an amine is used as the base, neutralize and return to the free amine, then subject to appropriate post-treatment such as filtration, washing with water, concentration and recrystallization according to the properties of the resulting reaction mixture. Sulfenamide is obtained.
Examples of the base used in this production method include raw material amine used in excess, tertiary amine such as triethylamine, alkali hydroxide, alkali carbonate, alkali bicarbonate, sodium alkoxide and the like. In particular, the reaction is carried out using excess raw material amine as a base or tertiary amine triethylamine, neutralizing the hydrochloride formed with sodium hydroxide, taking out the target product, and then removing the amine from the filtrate. A method of reuse is desirable.
As the solvent used in this production method, alcohol is desirable, and methanol is particularly desirable.

  For example, in N, N-methylcyclohexyl-2-benzothiazolsulfenamide, an aqueous sodium hypochlorite solution was added dropwise to N-methylcyclohexylamine at 0 ° C. or lower, and the oil layer was separated after stirring for 2 hours. Bis (benzothiazol-2-yl) disulfide, N-methylcyclohexylamine and the oil layer described above were suspended in methanol and stirred for 2 hours under reflux. After cooling, it is neutralized with sodium hydroxide, filtered, washed with water, concentrated under reduced pressure, and then recrystallized to obtain the target compound.

The content of these sulfenamide-based vulcanization accelerators is 0.1 to 10 parts by mass, preferably 0.5 to 5.0 parts by mass, and more preferably 0.1 to 100 parts by mass of the rubber component. It is desirable to be 8 to 2.5 parts by mass.
When the content of the vulcanization accelerator is less than 0.1 parts by mass, the vulcanization is not sufficiently performed. On the other hand, when it exceeds 10 parts by mass, bloom is a problem, which is not preferable.

Sulfur used in the present invention serves as a vulcanizing agent, and the content thereof is 0.3 to 10 parts by mass, preferably 1.0 to 7.0 parts by mass, with respect to 100 parts by mass of the rubber component. More preferably, it is desirable to set it as 3.0-7.0 mass parts.
If the sulfur content is less than 0.3 parts by mass, vulcanization will not be achieved sufficiently. On the other hand, if it exceeds 10 parts by mass, the aging performance of the rubber will be unfavorable.

Furthermore, it is preferable that the rubber composition of the present invention contains cobalt (a simple substance) and / or a compound containing cobalt from the viewpoint of improving the initial adhesion performance.
Examples of the cobalt-containing compound that can be used include at least one of a cobalt salt of an organic acid and a cobalt salt of an inorganic acid, such as cobalt chloride, cobalt sulfate, cobalt nitrate, cobalt phosphate, and cobalt chromate.
Preferably, it is desirable to use a cobalt salt of an organic acid from the viewpoint of further improving the initial adhesion performance.
Examples of the cobalt salt of an organic acid that can be used include at least one of cobalt naphthenate, cobalt stearate, cobalt neodecanoate, cobalt rosinate, cobalt versatate, cobalt tall oil, and the like. The organic acid cobalt may be a complex salt in which a part of the organic acid is replaced with boric acid. Specifically, a commercial name “manobond” manufactured by OMG Co., Ltd. may be used.

The (total) content of these cobalt and / or cobalt-containing compounds is 0.03 to 3 parts by mass, preferably 0.03 to 1 part by mass, with respect to 100 parts by mass of the rubber component, as the amount of cobalt. More preferably, it is desirable to set it as 0.05-0.7 mass part.
If the content of these cobalt amounts is less than 0.03 parts by mass, further adhesiveness cannot be exhibited. On the other hand, if it exceeds 3 parts by mass, the aging physical properties are greatly reduced, which is not preferable.

  The rubber composition of the present invention includes rubber products such as tires and conveyor belts in addition to the rubber component, sulfur, the sulfenamide vulcanization accelerator represented by the general formula (I), a cobalt compound, and the like. Commonly used compounding agents can be used as long as the effects of the present invention are not impaired, and for example, inorganic fillers such as carbon black and silica, softeners, anti-aging agents, and the like can be appropriately compounded depending on applications. it can.

  In the steel cord according to the present invention, the phosphorus content included as an oxide in the wire surface region from the surface of the peripheral surface brass plating layer to a depth of 5 nm inward in the wire radial direction is 1.5 atomic% or less. It is necessary to suppress. If the phosphorus content increases beyond 1.5 atomic%, the adhesion rate with the rubber is slowed accordingly. By setting the phosphorus content to 1.5 atomic% or less, it is possible to stably obtain excellent rubber adhesion regardless of the moisture content in the rubber.

Here, in the present invention (including examples and the like to be described later), the amount of phosphorus in the wire surface region of the brass plating layer is 20-30 μmφ so as not to be affected by the curvature of the wire using X-ray photoelectron spectroscopy. In this analysis area, the number of atoms existing in the wire surface region of the plating layer, that is, the number of atoms of C, Cu, Zn, O, P, and N is measured, and these C, Cu, Zn, O, P The phosphorus content was determined as the ratio of the number of P atoms when the total number of N atoms was 100. The number of atoms of each atom is determined by using the photoelectron counts of C: C _1S , O: O _1S , P: P _2P , Cu: Cu _{2p3 / 2} , Zn: Zn _{2p3 / 2} and N: N _1S , respectively. It was obtained by correcting with each sensitivity coefficient. For example, the number of detected atoms [P] of phosphorus can be obtained by the following formula.
[P] = F _p (P _2p sensitivity coefficient) × (P _2p photoelectron count per fixed time)

If the number of detected atoms is determined in the same manner for other atoms, the following formula is obtained from the results:
P (atomic%) = {[P] / ([Cu] + [Zn] + [C] + [O] + [N] + [P])} × 100
Thus, the relative atomic% of phosphorus can be obtained. Further, the distribution of elements in the depth direction from the peripheral surface to the inside in the wire radial direction can be measured in detail by performing argon etching or the like.
In addition, when the surface of the wire before the above analysis is covered with oil or contaminated with organic matter, the surface of the wire is washed with an appropriate solvent to perform an accurate analysis, and further, if necessary. Therefore, it is necessary to perform a light dry cleaning that does not modify the surface.

  In order to make the amount of phosphorus contained as an oxide in the surface layer of the wire 1.5 atomic% or less, a wire drawing pass schedule, a die entrance and approach shape and angle, a die material and a lubricant By adjusting the composition and the like individually or in combination, the amount of phosphorus is appropriately adjusted. In particular, in the final wire drawing process, a lubricant containing an extreme pressure additive is used in the same manner as usual, and it is excellent in the number of subsequent stages including the final pass or the final pass among the approximately 20 passes of the final wire drawing process. It is extremely effective to perform wire drawing by applying a die made of a material having both self-lubricating properties and machinability, for example, a sintered diamond die.

  The average thickness of the brass plating layer is preferably 0.13 to 0.30 μm. When the average thickness of the brass plating layer is less than 0.13 μm, the portion where the iron base is exposed increases and the initial adhesiveness is inhibited. On the other hand, when the average thickness exceeds 0.30 μm, the adhesive reaction is excessively caused by heat during use of the rubber article. Progresses and only fragile adhesion can be obtained.

  Moreover, in this invention, the ratio of copper with respect to the total amount of copper and zinc in the whole brass plating layer is 60-70 mass%, and the ratio of copper with respect to the total amount of copper and zinc in the said wire surface layer area | region is 15-45. It is preferably atomic%. When the ratio of copper to the total amount of copper and zinc in the entire brass plating layer is less than 60% by mass, wire drawing deteriorates, productivity is hindered by disconnection, and mass production becomes difficult. It becomes difficult to control the copper content to 15 atomic% or more. On the other hand, if it exceeds 70% by mass, the heat-resistant adhesiveness and moisture-resistant adhesiveness are lowered, and it becomes impossible to maintain sufficient durability against the environment to which the tire is exposed, and the copper content described later in the wire surface layer region Is difficult to control to 45 atomic% or less. Further, when the ratio of copper to the total amount of copper and zinc in the wire surface layer region is less than 15 atomic%, even if the amount of phosphorus in the wire surface region is limited to the above 1.5 atomic percent or less, rubber As a result, it becomes difficult to ensure better rubber adhesion. On the other hand, when it exceeds 45 atomic%, the heat resistant adhesiveness and moisture resistant adhesiveness are disadvantageously lowered.

  Furthermore, the diameter of the steel wire is preferably 0.40 mm or less. If the diameter exceeds 0.40 mm, the used rubber article is subjected to repeated strain under bending deformation, the surface strain becomes large, and buckling is likely to occur.

  The steel wire used in the present invention may be used as a single wire, or may be used as a steel cord obtained by twisting a plurality of wires, and is suitable as a reinforcing material for rubber articles, particularly tire carcass and belts. In particular, when the rubber-steel cord composite of the present invention is applied to a belt for a passenger car tire, particularly a radial tire for a passenger car, the speed of adhesion with the rubber is increased, thereby greatly increasing the vulcanization time of the tire. The effect which can be shortened can also be acquired. On the other hand, when applied to the carcass of truck and bus tires, especially truck and bus radial tires, the speed of adhesion to rubber increases at the bead part, so that the bead part durability is shortened along with shortening of the vulcanization time. It is possible to improve.

  The rubber-steel cord composite of the present invention comprises a rubber composition for steel cord coating containing the specific sulfenamide-based vulcanization accelerator and the specific steel cord. A rubber-steel cord composite comprising a steel cord adjacent to the composition is suitably used as a reinforcing material for improving the performance of industrial rubber products such as automobile tires and conveyor belts. When the rubber-steel cord composite of the present invention is used for a pneumatic tire, for example, in a tire having a carcass extending in a toroidal shape between a pair of beads and having a belt on the outer side in the tire radial direction, such carcass and belt The rubber-steel cord composite according to any one of the present invention described above is used for either or both of them, whereby a high-performance pneumatic tire excellent in durability can be obtained.

  In the present invention configured as described above, there is a vulcanization delay effect equivalent to or better than that of DCBS without using a vulcanization retarder that may cause problems such as deterioration in physical properties of rubber after vulcanization and blooming. Since the rubber composition containing a vulcanization accelerator having heat-resistant deterioration is used as a covering rubber such as a low-phosphorus steel cord with a low phosphorus content that inhibits the adhesion reaction, the generation of rubber burns is marked. In addition to being reduced, while maintaining processability and high heat-resistant adhesiveness when containing rubber, there is little change with time of the compounded rubber, and adhesion to steel cords etc. (adhesion after short-term vulcanization, heat-resistant adhesiveness) is remarkable A rubber-steel cord composite having excellent resistance is obtained, and a rubber composition further containing cobalt (a simple substance) and / or a compound containing cobalt further contains rubber such as tires and industrial belts. Rubber excellent adhesion durability between the steel cord and the like used in the product - the one steel cord composite is obtained.

  Next, the production examples of the vulcanization accelerator of the present invention and the examples and comparative examples of the rubber composition of the present invention will be described in more detail, but the present invention is not limited to these production examples and examples. It is not limited.

[Production Example 1: Synthesis of N, N-methylcyclohexyl-2-benzothiazolsulfenamide]
To 18.3 g (0.162 mol) of N-methylcyclohexylamine, 148 g of a 12% sodium hypochlorite aqueous solution was added dropwise at 0 ° C. or lower, and after stirring for 2 hours, the oil layer was separated. Bis (benzothiazol-2-yl) disulfide (39.8 g, 0.120 mol), N-methylcyclohexylamine (27.1 g, 0.240 mmol) and the oil layer described above were suspended in 120 ml of methanol and refluxed. Stir for 2 hours. After cooling, the solution is neutralized with 6.6 g (0.166 mol) of sodium hydroxide, filtered, washed with water, concentrated under reduced pressure, and recrystallized to obtain the desired N, N-methylcyclohexyl-2-benzothiazolsulfene. The amide was obtained as a white solid.

[Production Example 2: Synthesis of N, N- (2,6-dimethylcyclohexyl) ethyl-2-benzothiazolsulfenamide]
The same procedure as in Example 1 was carried out using 25.1 g (0.162 mol) of N-dimethylcyclohexylethylamine instead of N-methylcyclohexylamine, and N, N- (2,6-dimethylcyclohexyl) ethyl-2. -Benzothiazol sulfenamide was obtained as a white solid.

[Production Example 3: Synthesis of N, N- (2,6-diisopropylcyclohexyl) ethyl-2-benzothiazolsulfenamide]
The same procedure as in Example 1 was carried out using 34.2 g (0.162 mol) of N-diisopropylcyclohexylethylamine instead of N-methylcyclohexylamine. N, N- (2,6-diisopropylcyclohexyl) ethyl-2 -Benzothiazol sulfenamide was obtained as a white solid.

[Examples 1 to 3 and Comparative Examples 1 to 6]
Using a 2200 ml Banbury mixer, the rubber components, sulfur, novel vulcanization accelerators 1 to 3, the organic acid cobalt salt, and other compounding agents obtained in the above Production Examples 1 to 3 are shown in Table 1 below. An unvulcanized rubber composition was prepared by kneading and mixing, and Mooney viscosity and Mooney scorch time were evaluated by the following methods.
Next, each rubber composition obtained above was coated on a steel cord, vulcanized under the following conditions, and the obtained rubber-steel cord composites of Examples and Comparative Examples were obtained by the following method. Adhesion test evaluated adhesiveness and heat-resistant adhesiveness after vulcanization for a short time.
These results are shown in Table 1 below.

  The steel cord used was steel cord A brass-plated with Cu: 63 wt% and Zn: 37 wt% (as an oxide in the surface region of the wire from the surface of the brass plating layer to a depth of 5 nm inward in the radial direction of the wire) The amount of phosphorus contained: 2.5 atomic%) and steel cord B (same amount: 1.0 atomic%). In addition, the content of phosphorus contained as an oxide in the wire surface layer region from the surface of the brass plating layer to a depth of 5 nm inward in the wire radial direction was measured while performing argon etching.

(Evaluation method for Mooney viscosity and Mooney scorch time)
This was performed according to JIS K 6300-1: 2001.
The evaluation was expressed as an index with the value of Comparative Example 4 being 100. The smaller the value of Mooney viscosity, the better the workability, and the greater the Mooney scorch time, the better the workability.

(Adhesion test: Adhesion after short-term vulcanization, heat-resistant adhesion)
The above brass-plated steel cords (1 × 3 structure, strand diameter 0.30 mm) are arranged in parallel at 30 / inch intervals, and this steel cord is coated with a rubber composition (compounding described in Table 1 below) from both sides. A sample was prepared.
Each sample was subjected to an adhesion test in accordance with ASTM-D-2229. After vulcanization for a short time, each sample was vulcanized under the conditions of 160 ° C. × 7 minutes, and then the steel cord was drawn from the rubber for the rubber-steel cord composite by the above test method. Was visually observed and displayed as 0 to 100%, which was used as an index of adhesiveness after vulcanization for a short time. The larger the value, the better the adhesion after a short time vulcanization.
In addition, the heat-resistant adhesiveness was measured by leaving each sample in a gear oven at 100 ° C. for 15 days for 30 days, then pulling out the steel cord by the above test method, and visually observing the rubber coating state. And used as an index of each heat resistant adhesiveness. It shows that it is excellent in heat-resistant adhesiveness, so that a numerical value is large.

＊７：Ｎ−エチル−Ｎ−（２，６−ジメチルシクロヘキシル）−２−スルフェンアミド

＊８：Ｎ−エチル−Ｎ−（２，６−ジイソプロピルシクロヘキシル）−２−スルフェンアミド

* 1 to * 8 in Table 1 above are as follows.
* 1: N-phenyl-N′-1,3-dimethylbutyl-p-phenylenediamine (manufactured by Ouchi Shinsei Chemical Co., Ltd., trade name: rubber-steel cord composite xceller 6C)
* 2: N, N′-dicyclohexyl-2-benzothiazylsulfenamide (Ouchi Shinsei Chemical Co., Ltd., trade name: Noxeller DZ)
* 3: N-cyclohexyl-2-benzothiazylsulfenamide (Ouchi Shinsei Chemical Co., Ltd., trade name: Noxeller CZ)
* 4: N, N′-methyl-cyclohexyl-2-benzothiazylsulfenamide * 5: manufactured by OMG, trade name: Manobond C22.5, cobalt content 22.5% by mass
* 6: N-methylcyclohexyl-2-sulfenamide

* 7: N-ethyl-N- (2,6-dimethylcyclohexyl) -2-sulfenamide

* 8: N-ethyl-N- (2,6-diisopropylcyclohexyl) -2-sulfenamide

  As is apparent from the results of Table 1 above, Examples 1 to 3 within the scope of the present invention are more workable from evaluation of Mooney viscosity and Mooney scorch time than Comparative Examples 1 to 6 outside the scope of the present invention. In addition, it has been found that the adhesiveness after heat-curing for a short time and the heat-resistant adhesiveness are remarkably excellent.

  The rubber-steel cord composite of the present invention is suitable for rubber products that are directly vulcanized and bonded to rubber-steel cords in thick rubber products such as tires for passenger cars, trucks, buses, motorcycles, and belt conveyors. Can be applied to.

Claims (10)

A rubber composition containing a rubber component, sulfur, and a sulfenamide-based vulcanization accelerator represented by the following general formula (I) has a brass plating layer on the peripheral surface, and the surface of the brass plating layer A rubber-steel cord characterized in that a steel cord having a phosphorus content of 1.5 atomic% or less is adjacent to the inner surface in the wire radial direction up to a depth of 5 nm in the wire surface layer region. Complex.

  For 100 parts by mass of the rubber component, 0.3 to 10 parts by mass of sulfur, 0.1 to 10 parts by mass of the sulfenamide-based vulcanization accelerator represented by the general formula (I), and the entire brass plating layer The rubber-steel according to claim 1, wherein the ratio of copper to the total amount of copper and zinc is 60 to 70 mass%, and the ratio of copper to the total amount of copper and zinc in the wire surface layer region is 15 to 45 atomic%. Code complex.   The rubber-steel cord composite according to claim 1 or 2, wherein the brass plating layer has an average thickness of 0.13 to 0.30 µm.   The rubber-steel cord composite according to any one of claims 1 to 3, wherein the steel cord is formed by twisting a single wire of a steel wire or a plurality of the steel wires.   The rubber-steel cord composite according to claim 4, wherein a diameter of the steel wire is 0.40 mm or less.   The rubber-steel cord composite according to any one of claims 1 to 5, wherein the rubber composition further comprises 0.03 to 3 parts by mass with respect to 100 parts by mass of the rubber component as a cobalt amount of an organic acid cobalt salt. body. R < ¹² > -R < ¹⁵ > in the said general formula (I) is a hydrogen atom, The rubber-steel cord composite as described in any one of Claims 1-6. The rubber-steel cord composite according to any one of claims 1 to 7, wherein R ¹¹ in the general formula (I) is a hydrogen atom and x is 1.   The rubber-steel cord composite according to any one of claims 1 to 8, wherein the rubber component contains at least one of natural rubber and polyisoprene rubber.   The rubber-steel cord composite according to any one of claims 1 to 8, wherein the rubber component comprises a natural rubber of 50 mass% or more and the balance is a synthetic rubber.